Bug 16550: Add test to NewsChannels.t

Bug 16550: Add test to NewsChannels.t

To test: Run t/db_dependent/NewsChannels.t

Tests adding and retreiving a news item without expiration date.
This test should fail without patch for Bug 16550 and pass OK with patch.

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 521bfb082732c00e33843ee44cbb8ff2a2c1d56d)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>